1. Field of the Invention
This invention relates to sensing and control techniques for laundry apparatus, and is particularly concerned with methods and apparatus for sensing the moisture content of a clothes load within a dryer and controlling the operation of the clothes dryer on a digital basis.
2. Description of the Prior Art
U.S. Pat. No. 3,702,030 discloses a high voltage sensor circuit for an integrated circuit control that produces repetitive pulses when the clothes load is drier than a given dryness level for resetting a second counter to prevent the second counter from resetting a first counter. The first counter, upon reaching a predetermined count, ends the sense portion of the drying cycle. Similar circuits are utilized in U.S. Pat. Nos. 3,762,064 and 3,769,716.
U.S. Pat. No. 3,621,293 discloses the use of a field effect transistor for sensing voltage build up on a capacitor in a dryer control.
U.S. Pat. No. 4,215,486 discloses a dryer control circuit which utilizes the output of an oscillator, which is frequency dependent on the dryness of the clothes, to feed an amplifier, the output level of which is dependent on the frequency of the oscillator. The output of the amplifier is fed to a comparator which compares the amplifier output with a reference voltage and shuts down the dryer when that voltage is reached.